可以阻止Django截断长表名吗?

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我正在将Django与现有的Oracle DB配合使用(即Django未创建表的数据库).因此，在我的模型中，我必须通过在Meta类中为db_table指定一个值来指示表名.我遇到了问题，因为我希望访问的表与我拥有凭据的用户属于不同的用户.我有权查看表(在SQL Developer中这样做很容易).

I'm using Django with an existing Oracle DB (i.e., one where the tables were NOT created by Django). So in my models I am having to indicate the table name by specifying a value for db_table in the Meta class. I'm running into problems becuase the tables I wish to access belong to a different user than the one I have credentials for. I am authorized to view the tables (no trouble doing it in SQL Developer).

如果Oracle表的名称原本超过30个字节，则Django会砍掉该名称的最后四个字节，并用表名其余部分的可重复的4字节哈希替换它们.这对于Django自己制作的表来说都是一件好事.通常，访问现有数据库中的表也不会出现问题(例如我的例子)，因为Oracle本身会将名称限制为30个字节.

When the name of an Oracle table would otherwise be over 30 bytes, Django chops off the last four bytes of the name and replaces them with a repeatable 4-byte hash of the rest of the table’s name. This is all well and good for tables Django makes itself. It also normally wouldn’t be a problem for accessing tables in existing DBs (as in my case) since Oracle itself would’ve constrained the names to 30 bytes.

问题是Django没有单独的功能来指出该表属于另一个用户.因此，我使用的是点语法解决方法(只需将db_table设置为例如"USERNAME.MY_29_BYTE_TABLE_NAMEXXXXXXXX")，但是由于这会导致整体表名超过30个字节，因此Django会执行其截断技巧并尝试查询不存在的表名.

The problem is that Django doesn’t have a separate facility for noting that the table belongs to another user. So I'm using a dot-syntax workaround (by just setting db_table as, e.g. "USERNAME.MY_29_BYTE_TABLE_NAMEXXXXXXXX"), but since this leads to the overall table name exceeding 30 bytes, Django does its truncation trick and tries to query against a table name that doesn’t exist.

是否有防止这种现象的方法，或以其他方式指定用户与表名的区别?

Is there a way to prevent this behavior, or a different way to specify the user separate from the name of the table?

推荐答案

截断由 quote_name 方法，该方法遵循SQL92要求，并使用硬编码值 max_name_length .

Truncate is caused at Oracle Django DB backend by quote_name method, which follows SQL92 requirements and uses hard-coded value max_name_length.

您可以通过创建自定义数据库后端或通过Monkeypatch这样的方式来覆盖此行为:

You can override this behavior by creating custom DB backend or by monkeypatch like this:

from django.db.backends.oracle.base import DatabaseOperations DatabaseOperations.max_name_length = lambda s: <NEW_MAX_VALUE>

尚不清楚为什么表名需要超过30个字符，因为它违反了 Oracle架构对象命名规则.

It's not really clear why you need more than 30 characters in table name, as it violates Oracle Schema Object Naming Rules.